Many products are designed to include modules that can be removed from a main housing for service or replacement. Cables, in particular power cables, attach into such modules. In order to remove the module from the main housing for service, the power cable should first be removed from the module as a safety precaution. Failure to remove the power cable from the module prior to removal of the module from the main housing exposes service personnel to dangerous voltage levels carried by the cables.
Underwriter's Laboratories (UL) requires power cables be secured to their respective modules in a manner that requires a tool to remove the cable from the module. By requiring a tool for removal of the power cable from the module, inadvertent removal of the power cable is prevented.